Empirical formulas, 333 prob

Calculate the number of empirical formula units in the molecule and write the qq (q http //now.brookscole.com/ molecular formula. cracoUceZe and click Coached Prob-... 

A common procedure to reduce basis-set truncation error is to do a series of calculations using one method with two, three, or four increasingly larger basis sets and extrapolate the results to what one hopes is a value close to the complete-basis-set (CBS) limit. Examples are the extrapolation done with the formula (15.23) (Prob. 15.21) and with the formula (15.88) (Prob. 15.22) to estimate the CBS HE limit for H2O. When a method such as CC that includes correlation is used, the extrapolation is commonly done in two steps. One first does HE calculations with a series of basis sets to estimate the CBS HE energy limit E . Then one does a series of CC calculations with the same series of basis sets and uses an empirical extrapolation formula to estimate the CBS correlation energy E. The estimate of the CBS molecular energy is then found as E + 2 . See the discussion after Eq. (16.31). 

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See also in sourсe #XX -- [ ]

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